Streaming made music effortless, but it also blurred what we actually hear. Most services stream lossy, recompressed audio tuned for bandwidth rather than fidelity. "Hi-res audio" is the umbrella term for files that keep more of the original recording. This guide explains the terms — lossless, bit depth, sample rate, and DSD — in plain language, so the numbers on a download page finally mean something.
Lossy vs Lossless
Lossy formats like MP3 and AAC permanently discard audio data to shrink the file. Done well, the loss is hard to hear, which is why these formats won the portable-music era. Lossless formats like FLAC and ALAC compress the file without throwing anything away — decompress one and you get a bit-for-bit copy of the original. Hi-res audio is almost always lossless, because the entire point is to preserve detail, not discard it.
Bit Depth: The Dynamic Range
Bit depth controls how precisely each moment of sound is measured, which sets the dynamic range — the gap between the quietest and loudest passages a file can hold. CD audio is 16-bit, giving about 96 dB of range. Studio masters are commonly 24-bit, with a theoretical range beyond 140 dB. In practice the headroom matters most during production, but a 24-bit file preserves quiet detail and fade tails that a lower bit depth can crush.
Sample Rate: How Often Sound Is Measured
Sample rate is how many times per second the waveform is captured, measured in kHz. CD audio is 44.1kHz; hi-res files run 96kHz, 192kHz, and higher. A higher sample rate raises the highest frequency a file can represent and gives converters more room to work cleanly. The audible benefit above a certain point is debated, but high-sample-rate masters remain the closest thing to the studio source.
Where DSD Fits In
DSD (Direct Stream Digital) is a different approach entirely. Instead of multi-bit samples, it uses a single bit at an extremely high rate — DSD64 runs at 2.8MHz. It is the format behind SACDs and many audiophile reissues. DSD cannot be processed like PCM without conversion, so playback usually means either converting to PCM or sending the raw stream to a compatible DAC using DoP (DSD over PCM).
Do You Need Special Hardware?
For lossless PCM up to high sample rates, a good pair of headphones and a clean output path are enough to hear the difference from a lossy stream. To get the most from very high sample rates or native DSD, an external USB DAC helps — it handles the conversion outside the noisy environment of a phone. The most important link, though, is a player that does not silently resample or recompress your files on the way out.
Keeping a Bit-Perfect Path
Hi-res files only matter if nothing degrades them between storage and your ears. PhaseShift plays FLAC, ALAC, WAV, AIFF and native DSD through a pipeline built to avoid unnecessary resampling, and shows a "no resampling" badge when the path to your DAC is bit-perfect. It is a way to confirm that the resolution you paid for is the resolution you actually hear.